Materials which can provide aromas with sweet woody, citrusy, vetiver, musky, woody/peppery, woody/leathery, hay and green nuances and/or woody fragrance notes are known in the art of perfumery. Natural materials which provide such fragrances and contribute desired nuances to perfumery compositions, such as natural vetiver oil, are frequently difficult to obtain and/or are high in cost or vary in quality from one batch to another and/or are generally subject to the usual variations of natural products.
There is accordingly a continuing effort to find synthetic materials which will replace the essential fragrance notes provided by natural essential oils or compositions thereof having a vetiver aroma. Unfortunately, many of these synthetic materials either have the desired nuances only to a relatively small degree or else contribute undesirable or unwanted odor to the composition. The search for materials which can provide a more refined vetiver fragrance has been difficult and relatively costly in the areas of both natural products and synthetic products.
Acetonaphthones, particularly octahydro acetonaphthone, are known in perfumery particularly for providing amber or fruity amber fragrance notes which do not discolor with age. Thus, U.S. Pat. No. 3,911,018, issued on Oct. 7, 1975, covers an isomer of octahydrotetramethyl acetonaphthone having the structure: ##STR3## wherein the dashed lines represent methyl groups "cis" to one another.
U.S. Pat. No. 3,911,018 also covers processes for producing isomer mixtures of octahydro-2',3',8',8'-tetramethyl-(2' or 3')-acetonaphthone having the generic formula: ##STR4## wherein one of the wavy lines is a carbon-carbon double bond and the other of the wavy lines represent carbon-carbon single bonds. The mixtures produced by the processes of U.S. Pat. No. 3,911,018 contain from 70 mole percent up to 99 mole percent of compounds having the generic structure: ##STR5## Such a generic structure includes individual compounds having an acetyl group at the 2' position, compounds having an acetyl group at the 3' position and mixtures of such compounds. The generic structures set forth above also include geometric isomers wherein the acetyl group is cis to the methyl group on the carbon atom adjacent to that bonded to the acetyl moiety and where the acetyl group is "trans" to the methyl group on the carbon atom adjacent to that bonded to the acetyl moiety. Furthermore, the products of U.S. Pat. No. 3,911,018 are indicated to be produced by means of a two-step reaction:
1. Reacting myrcene with 3-methyl-3-penten-2-one either:
a. in the presence of a Lewis acid at tempertures in the range of from 0.degree. up to 50.degree. C. thereby producing a mixture of geometric isomers which are Diels-Alder adducts which are alkenyl acetyl dimethyl substituted cyclohexenes represented by the structure: ##STR6## or: b. reacting myrcene with 3-methyl-3-penten-2-one without using a catalyst at temperatures in the range of 120.degree. C. up to 180.degree. C. forming a mixture of isomers (including geometric isomers) of alkenyl acetyl dimethyl substituted cyclohexenes having the generic structure: ##STR7##
2. Cyclizing the resulting substituted cyclohexenes (Diels-Alder adducts) by means of heating same in the presence of phosphoric acid or dilute sulfuric acid (50-80%) or boron trifluoride or complexes thereof, e.g., boron trifluoride etherate.
Kagi, et al, Journal of the Society of Cosmetic Chemists, (Great Britain), 1973, pages 1-14, "Catalyzed Diels-Alder Reactions in the Synthesis of Perfumery Materials", discloses a synthesis of one of the isomers capable of being produced by the processes of the invention, which isomer has the structure: ##STR8## by means of reacting myrcene and 3-bromo-4-methylpent-3-ene-2-one to give the bromo adduct having the structure: ##STR9## and then dehydrobrominating the said bromo adduct to give the dienone. Kagi, et al, reports that this particular isomer has "a very powerful, musk-ambergris odour" on page 10. The novel isomer as well as the mixture of isomers produced by the instant invention have properties which are advantageous and unexpected with respect to the particular isomer of Kagi, et al.
In addition, British Pat. No. 896,039 entitled "Method of Producing Derivatives of the 1,1-Dimethyl-octahydronaphthalene Series" discloses the generic process: ##STR10## wherein R.sub.2, R.sub.3 and R.sub.4 are disclosed to be the same or different and hydrogen or alkyl and R.sub.1 is disclosed to be hydroxy, alkyl or alkoxy. The British patent discloses this process to be useful for producing products "resembling the well known class of violet perfumes". Indeed, Example 5 of the British patent alleges that the compound 1,1,6,6-Tetramethyl-7-ketomethyl-Octalin produced by (1) reacting myrcene and mesityl oxide thermally followed by (2) subsequent cyclization, has a pleasant "woody ambergris smell". However, a repetition of the teachings of this British patent gives rise to the following results: ##STR11##
In addition to the above-mentioned British patent, the above stated sequence of:
1. Diels-Alder Reaction to form Diels-Alder adducts followed by
2. Cyclization of the Diels-Alder adducts is disclosed in detail by Ohloff Ann. 606,100 (1957 ).
Further, cyclization reactions of Diels-Alder adducts of myrcene and a dienophile are set forth in U.S. Pat. No. 3,076,022. This patent discloses interalia, preparation of the thermal Diels-Alder adduct of myrcene and methyl isopropenyl ketone and subsequent acid cyclization to a product said to possess "an intense ambergris-like note". Repetition of the process as disclosed gave rise to a product possessing fruity, woody, pineapple notes rather than an ambergris-like note.
Ohloff [Chemistry of Odoriferous and Flavoring Substances ] pp. 185-240 (at page 192) Fortschritte und der Chemischen Forschung Vol. 12, Part 2, 1969, discloses a compound having the structure: ##STR12## Ohloff indicates that materials of this nature have "resiny odors" like olibanum, with amber type undertones.
However, none of the prior art substituted acetonaphthone compounds possess aromas having sweet woody, vetiver, citrusy, musky, woody/peppery, woody/leathery, hay and green nuances and/or woody fragrance notes of the compounds of our invention.
2-Acetyl-3,4,4a,5,6,7-hexahydro-4a,8-dimethylnaphthalene having the structure: ##STR13## has been determined to occur naturally in vetiver oil. It has a sweet, woody, musky and herbal aroma, from a perfumery standpoint, and a musky, oriental, woody, vetiver aroma profile and a musky, oriental, woody, vetiver, astringent flavor character, having potential uses in blueberry and pear flavors. Although having similar functional groups of the compound of the instant invention, the structure and fragrance profiles are different in kind from the mixtures and isomers of the instant invention.
U.S. Pat. No. 3,845,135, issued on Oct. 29, 1974 is directed to the manufacture of beta ionones but erroneously sets forth a structure at column 1, line 65 thereof as follows: ##STR14## Obviously a printing error occurred showing a bond between the group "R.sup.2 " and a methyl group.
Other acetyl hexahydro naphthalenes are known, but the structures of such compounds are different in kind from those of the instant invention. Thus, an article by Watt and Corey in Tetrahedron Letters, #46, pages 4651-4654, 1972, discloses compounds having the structures: ##STR15##